Lens driving device, camera module, and camera-equipped portable terminal

ABSTRACT

A lens driving device comprising: an autofocus driving unit in which an autofocus movable part is elastically supported by an autofocus fixed part due to an elastic support part; and an auxiliary magnet which, in a reference position of the autofocus movable part, has a movement direction action force of zero relative to the autofocus movable part and which generates the movement direction action force in the opposite direction to a restoring force of the elastic support part when the autofocus movable part has moved.

TECHNICAL FIELD

The present invention relates to an auto-focusing lens driving device, acamera module having an auto focus function, and a camera-equippedmobile terminal.

BACKGROUND ART

In general, a small-sized camera module is mounted in mobile terminalssuch as a smartphone. The lens driving device has an auto focus functionof automatically performing focusing for capturing a subject(hereinafter referred to as “AF (Auto Focus) function”), and a shakecorrection function (hereinafter referred to as “OIS (Optical ImageStabilization) function”) of optically correcting hand shake (vibration)upon capturing an image to reduce the irregularities of the image (forexample, PTL 1).

The auto-focusing and shake-correcting lens driving device includes anauto-focusing driving part (hereinafter referred to as “AF drivingpart”) for moving the lens part in the light axis direction, and ashake-correcting driving part (hereinafter referred to as “OIS drivingpart”) for swaying the lens part in a plane orthogonal to the light axisdirection.

The AF driving part includes, for example, an auto-focusing coil part(hereinafter referred to as “AF coil part”) disposed around the lenspart, and an auto-focusing magnet part (hereinafter referred to as “AFmagnet part”) disposed separately from the AF coil part in the radialdirection. An auto-focusing movable part (hereinafter referred to as “AFmovable part”) including the lens part and the AF coil part is movedwith respect to an auto-focusing fixing part (hereinafter referred to as“AF fixing part”) including the AF magnet part in the light axisdirection by use of a driving force of a voice coil motor composed ofthe AF coil part and the AF magnet part, and thus focusing isautomatically performed. The AF movable part and the AF fixing part arecollectively referred to as “auto-focusing unit (AF unit).”

The OIS driving part includes a shake-correcting magnet part(hereinafter referred to as “OIS magnet part”) disposed at the AF unit,and a shake-correcting coil part (hereinafter referred to as “OIS coilpart”) disposed separately from the OIS magnet part in the light axisdirection, for example. A shake-correcting movable part (hereinafterreferred to as “OIS movable part”) including the AF unit and the OISmagnet part is supported by a supporting member so as to be separatedfrom a shake-correcting fixing part (hereinafter referred to as “OISfixing part”) including the OIS coil part in the light axis direction.The OIS movable part is swayed in a plane orthogonal to the light axisdirection by use of a driving force of a voice coil motor composed ofthe OIS magnet part and the OIS coil part, and thus shake correction isperformed.

In the lens driving device disclosed in PTL 1, an elastic supportingpart (an upper leaf spring and a lower leaf spring) connects a lensholder (as a part of the AF movable part) in which the AF coil part isdisposed at the outer peripheral surface, with a magnet holder (as apart of AF fixing part) in which the AF magnet part (which also servesas the OIS magnet part) is disposed. At the time of focusing, the AFmovable part moves in the light axis direction until the driving force(driving power) of the voice coil motor of the AF driving part and therestoration force of the elastic supporting part are equivalent to eachother, and the AF movable part is held in that state.

When the rigidity of the elastic supporting part can be furtherincreased in the lens driving device disclosed in PTL 1, the unnecessaryresonance frequency is set to a high value, and servo stability isimproved. In addition, the OIS tilt characteristics can be improved.

CITATION LIST Patent Literature

-   PTL 1-   Japanese Patent Application Laid-Open No. 2013-210550

SUMMARY OF INVENTION

However, the elastic supporting part that elastically supports the AFmovable part with respect to the AF fixing part is required to have apredetermined spring constant. Therefore, it is difficult to increasethe rigidity of the elastic supporting part while satisfying a requiredspring constant.

An object of the present invention is to provide a lens driving devicewhich can improve the OIS tilt characteristics and can increase thedegree of freedom of the servo design in a structure in which the AFmovable part and the AF fixing part are elastically supported, and toprovide a camera module and a camera-equipped mobile terminal includingthe lens driving device.

A lens driving device according to an embodiment of the presentinvention includes: an auto-focusing driving part, and an auxiliarymagnet, the auto-focusing driving part including: an auto-focusing coilpart disposed at a periphery of a lens part; an auto-focusing magnetpart having a yoke part and disposed separately from the auto-focusingcoil part in a radial direction; and an elastic supporting partconfigured to elastically support an auto focus movable part includingthe auto-focusing coil part with respect to an auto focus fixing partincluding the auto-focusing magnet part, the auto-focusing driving partbeing configured to perform automatic focusing by moving the auto focusmovable part in a light axis direction with respect to the auto focusfixing part by utilizing a driving force of a voice coil motor composedof the auto-focusing coil part and the auto-focusing magnet part, theauxiliary magnet being configured to have no acting force in a movementdirection with respect to the auto focus movable part at the referenceposition of the auto focus movable part, and being configured togenerate an acting force in a movement direction in a direction oppositeto a direction of a restoration force of the elastic supporting partwhen the auto focus movable part is moved.

A camera module according to an embodiment of the present inventionincludes: the lens driving device; a lens part mounted to the auto focusmovable part; and an image capturing part configured to capture asubject image imaged by the lens part.

A camera-equipped mobile terminal according to an embodiment of thepresent invention includes the camera module.

According to the present invention, even when the rigidity of theelastic supporting part is increased, a desired spring constant as awhole can be achieved. By increasing the rigidity of the elasticsupporting part, unnecessary resonance frequency is set to a high valueand the servo stability is improved, and thus, the degree of freedom ofthe servo design is increased. In addition, the OIS tilt characteristicscan be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a front view of a smartphone in which a camera moduleaccording to an embodiment of the present invention is mounted, and FIG.1B is a rear view of the smartphone;

FIG. 2 is a perspective view of an external appearance of the cameramodule;

FIG. 3 is an exploded perspective view of the camera module;

FIG. 4 is an exploded perspective view of a lens driving device;

FIG. 5 is an exploded perspective view of an OIS movable part;

FIG. 6 is a plan view of the OIS movable part;

FIG. 7 is a bottom view of the OIS movable part;

FIG. 8 is a plan view of a lens holder;

FIG. 9 is an enlarged view of a region around a tying part;

FIG. 10 is an exploded perspective view of the OIS fixing part;

FIG. 11 is a plan view illustrating the positions of a Hall device and aposition detection magnet;

FIG. 12 is a side view illustrating the positions of the Hall device anda first position detection magnet;

FIG. 13 is a perspective view illustrating the positions of the Halldevice and the position detection magnet; and

FIG. 14 illustrates an example of an acting force generated at an AFmovable part in a movement direction (the Z direction).

DESCRIPTION OF EMBODIMENT

In the following, an embodiment of the present invention is described indetail with reference to the drawings. FIGS. 1A and 1B illustratesmartphone M in which camera module A according to the embodiment of thepresent invention is mounted. FIG. 1A is a front view of smartphone M,and FIG. 1B is a rear view of smartphone M.

For example, smartphone M is provided with camera module A as a backside camera OC. Camera module A has an auto focus function and a shakecorrection function, and can capture an image without image blurring byautomatically performing focusing at the time of capturing a subject andby optically correcting hand shake (vibration) caused at the time ofcapturing an image.

FIG. 2 is a perspective view of an external appearance of camera moduleA. FIG. 3 is an exploded perspective view of camera module A. Asillustrated in FIG. 2 and FIG. 3, descriptions will be made with anorthogonal coordinate system (X, Y, Z) in the present embodiment. Alsoin the drawings described later, descriptions will be made with anorthogonal coordinate system (X, Y, Z). Camera module A is mounted suchthat the vertical direction (or horizontal direction) is the Xdirection, the horizontal direction (or vertical direction) is the Ydirection, and the front-rear direction is the Z direction at the timeof actually capturing an image with smartphone M. That is, the Zdirection is the light axis direction, the upper side in the drawing isthe light reception side in the light axis direction (also referred toas “macro position side”), and the lower side is the imaging side in thelight axis direction (also referred to as “infinity position side”).

Camera module A includes a lens part (not illustrated) in which a lensis housed in a lens barrel having a cylindrical shape, auto-focusing andshake-correcting lens driving device 1, an image capturing part (notillustrated) that captures a subject image imaged with the lens part,shield cover 2 that covers the entirety, and the like.

As viewed in the light axis direction, shield cover 2 is a capped squarecylindrical body having a square shape in plan view. Circular opening 2a is formed in the top surface of shield cover 2. A lens part (notillustrated) is exposed to the outside through opening 2 a. Shield cover2 includes, at the bottom part, engagement piece 2 b for mounting tolens driving device 1 (base member 23). Engagement piece 2 b protrudesdownward from the bottom part of shield cover 2. In addition, slit 2 cis formed in engagement piece 2 b to facilitate elastic deformation.

The image capturing part (not illustrated) includes an imaging device(not illustrated), and is disposed on the imaging side in the light axisdirection of the lens driving device 1. The imaging device (notillustrated) is composed of, for example, a CCD (charge coupled device)image sensor, a CMOS (complementary metal oxide semiconductor) imagesensor, or the like. The imaging device (not illustrated) captures asubject image imaged by a lens part (not illustrated).

FIG. 4 is an exploded perspective view of lens driving device 1. Asillustrated in FIG. 4, lens driving device 1 includes OIS movable part10, OIS fixing part 20, supporting member 30 and the like. OIS movablepart 10 includes an OIS magnet part serving as a component of the OISvoice coil motor, and sways in the XY plane at the time of shakecorrection. OIS fixing part 20 includes an OIS coil part. That is, theOIS lens driving part of lens driving device 1 is of a moving magnettype. OIS movable part 10 is the “AF unit” including the AF drivingpart.

OIS movable part 10 is disposed on the light reception side in the lightaxis direction relative to OIS fixing part 20 and is separated from OISfixing part 20. OIS movable part 10 is coupled with OIS fixing part 20by supporting member 30. To be more specific, supporting member 30 iscomposed of six suspension wires extending along the Z direction(hereinafter referred to as “suspension wire 30”). One end (upper end)of suspension wire 30 is fixed to OIS movable part 10 (upper elasticsupporting part 13), and the other end (lower end) of suspension wire 30is fixed to OIS fixing part 20 (coil substrate 21). OIS movable part 10is supported by suspension wire 30 such that OIS movable part 10 cansway in the XY plane.

In the present embodiment, in six suspension wires 30, suspension wires31A and 31B are used as a signal path of Hall device 161 (see FIG. 5)(signal suspension wire), suspension wires 32A and 32B are used as apower feeding path of Hall device 161 (Hall device feeding suspensionwire), and suspension wires 33A and 33B are used as a power feeding pathof AF coil part 112 (see FIG. 5) (coil feeding suspension wire). It isto be noted that the number of suspension wires 30 are not limited, andseven or more suspension wires 30 may be provided.

FIG. 5 is an exploded perspective view of OIS movable part 10. FIG. 6 isa plan view of OIS movable part 10. FIG. 7 is a bottom view of OISmovable part 10. As illustrated in FIG. 5 to FIG. 7, OIS movable part 10(AF unit) includes AF movable part 11, AF fixing part 12, upper elasticsupporting part 13, lower elastic supporting part 14 and the like. AFmovable part 11 is coupled with AF fixing part 12 by upper elasticsupporting part 13 and lower elastic supporting part 14.

AF movable part 11 includes a coil part serving as a component of an AFvoice coil motor, and moves in the light axis direction at the time offocusing. AF fixing part 12 includes a magnet part serving as acomponent of the AF voice coil motor. That is, the AF lens driving partof lens driving device 1 is of a moving coil type.

AF movable part 11 includes lens holder 111, AF coil part 112, andposition detection magnet 15.

Lens holder 111 is a member having a cylindrical shape, and a lens part(not illustrated) is fixed on the inner peripheral surface by bonding orscrewing. Lens holder 111 includes, at the lower half portion of theperipheral surface, coil winding part 111 a having a chamferedquadrangular shape. Lens holder 111 includes, at four portionsintersecting the X direction and the Y direction (hereinafter referredto as “cross direction”) of the upper half portion of the peripheralsurface, protruding parts 111 b that radially outwardly protrude.Protruding parts 111 b radially outwardly protrude over coil windingpart 111 a. The top surface of protruding part 111 b serves as a lockingpart for restricting the movement of AF movable part 11 to the lightreception side in the light axis direction, and the bottom surface ofprotruding part 111 b serves as a locking part for restricting themovement of AF movable part 11 to the imaging side in the light axisdirection.

Lens holder 111 includes, at four portions intersecting the directions(hereinafter referred to as “diagonal direction”) rotated by 45 degreesfrom the cross direction of the upper half portion of the peripheralsurface, protruding parts 111 c and 111 d. Protruding parts 111 c and111 d serve as upper spring fixing parts (hereinafter referred to as“upper spring fixing parts 111 c” and “upper spring fixing parts 111 d”)for fixing upper elastic supporting part 13.

Upper spring fixing parts 111 c and 111 d include upper bosses 111 e forpositioning and fixing upper elastic supporting part 13. In upper springfixing parts 111 c and 111 d, two upper spring fixing parts 111 clocated at first diagonal parts include tying parts 111 h that radiallyoutwardly protrude. In upper spring fixing parts 111 c and 111 d, twoupper spring fixing parts 111 d located at second diagonal parts includemagnet housing parts 111 i for disposing position detection magnet 15.

Lens holder 111 includes, at the four corners of the bottom surface,lower spring fixing parts 111 f for fixing lower elastic supporting part14. Lower spring fixing parts 111 f include lower bosses 111 g forpositioning and fixing lower elastic supporting part 14.

AF coil part 112 is an air-core coil that is energized at the time offocusing, and is wound around the outer peripheral surface of coilwinding part 111 a of lens holder 111. One end of AF coil part 112 istied to one tying part 111 h of lens holder 111 and the other end of AFcoil part 112 is tied to the other tying part 111 h.

FIG. 8 and FIG. 9 illustrate a structure of tying part 111 h of lensholder 111. FIG. 8 is a plan view of lens holder 111. FIG. 9 is anenlarged view illustrating a region around tying part 111 h. Normally,AF coil part 112 is wound around coil winding part 111 a of lens holder111 by use of a winder, and thereafter both end portions thereof aretied to tying parts 111 h. Conventionally, the tying part is disposedsuch that the base portion thereof is located on the outside relative tothe coil winding area. The reason for this is that, when the baseportion of the tying part is located on the inside relative to the coilwinding area, the task of sequentially tying the end portion of AF coilpart 112 from the base portion of the tying part is significantlydifficult.

In view of this, in the present embodiment, tying part 111 h has atapered shape whose diameter is reduced toward the inner side in theradial direction, that is, toward base portion 111 j. In this case, byperforming the tying with tension, the end portion of AF coil part 112is smoothly moved to the base portion 111 j side, and is wound in array.In this manner, it is possible to dispose tying part 111 h such thatbase portion 111 j is located on the inner side relative to the coilwinding area. That is, the outer dimension of lens holder 111 can bereduced without impairing the efficiency of the tying.

Position detection magnet 15 is disposed at magnet housing part 111 iformed at upper spring fixing part 111 d of lens holder 111. Detectionmagnet 15 that is disposed at a position on the side corresponding toposition detection part 16 (hereinafter referred to as “first positiondetection magnet 15A” not illustrated in FIG. 5) is practically used forposition detection of AF movable part 11. The other position detectionmagnet 15 (hereinafter referred to as “second position detection magnet15B”) is a dummy magnet that is not used for the position detection ofAF movable part 11. Second position detection magnet 15B is disposed forbalancing a magnetic force which acts on AF movable part 11 andstabilizing the orientation of AF movable part 11. Specifically, whensecond position detection magnet 15B is not disposed, a one-sidedmagnetic force is exerted on AF movable part 11 due to the magneticfield generated at magnet part 122, and the orientation of AF movablepart 11 becomes unstable, and therefore, second position detectionmagnet 15B is disposed to prevent such a situation.

AF fixing part 12 includes magnet holder 121, magnet part 122, andposition detection part 16. While FIG. 5 illustrates a state wheremagnet holder 121 is attached on magnet part 122, magnet part 122 isattached after AF movable part 11 is inserted to magnet holder 121 inpractice.

Magnet holder 121 has a quadrangular cylindrical shape which is squarein plan view. Magnet holder 121 includes arc grooves 121 a recessedinward in the radial direction at four coupling parts (four sides alongthe Z-axis direction) of the side walls. Suspension wires 30 aredisposed at arc grooves 121 a.

Magnet holder 121 includes, at the upper inner peripheral surface, fourstopper parts 121 b that protrude inward in the radial direction. Upperspring fixing part 111 d of lens holder 111 is fitted into cutout part121 c where stopper part 121 b is not formed.

Magnet holder 121 includes, at four corners of the upper part, upperspring fixing parts 121 d that fix upper elastic supporting part 13.Upper spring fixing part 121 d includes upper boss 121 e for positioningand fixing upper elastic supporting part 13. The top surface of cornerportion 121 f of upper spring fixing part 121 d is slightly recessedwith respect to the surrounding portions so that a gap is formed whenupper elastic supporting part 13 is attached thereto. In addition,corner portion 121 f of upper spring fixing part 121 d includes wireinsertion part 121 g through which suspension wire 30 is inserted.

Magnet holder 121 includes, at the four corners of the bottom surface,lower spring fixing parts (not illustrated) that fix lower elasticsupporting part 14. Lower spring fixing parts (not illustrated) includelower bosses 121 h for fixing and positioning lower elastic supportingpart 14.

Magnet part 122 includes four cuboid permanent magnets 122A to 122D andcoupling yoke 123 and 124. Permanent magnets 122A to 122D are disposedalong the internal surfaces of the four side walls of magnet holder 121.Permanent magnets 122A and 122C are disposed to face each other in the Ydirection, and permanent magnets 122B and 122D are disposed to face eachother in the X direction. Protruding part 111 b of lens holder 111 islocated in space S between magnet part 122 and stopper part 121 b ofmagnet holder 121.

Permanent magnets 122A to 122D are magnetized such that a magnetic fieldorthogonal to the radial direction is formed at AF coil part 112. Forexample, permanent magnets 122A to 122D are magnetized such that theinner periphery side and the outer periphery side thereof are set to Npole and S pole, respectively. The AF voice coil motor is composed ofmagnet part 122 and AF coil part 112. In addition, magnet part 122serves as the AF magnet part and as the OIS magnet part.

One of end surfaces of permanent magnet 122A in the longitudinaldirection, and an end surface of adjacent permanent magnet 122B in thelongitudinal direction are coupled with each other with coupling yoke123 having a W-shape in plan view. Coupling yoke 123 includes yoke part123 a at one end portion thereof, and yoke part 123 b at the other endportion thereof. Specifically, yoke part 123 a is disposed at an endsurface of permanent magnet 122A in proximity to first positiondetection magnet 15A, and yoke part 123 b is disposed at an end surfaceof permanent magnet 122B in proximity to first position detection magnet15A.

Likewise, one of end surfaces of permanent magnet 122C in thelongitudinal direction, and an end surface of adjacent permanent magnet122D in the longitudinal direction is coupled with each other withcoupling yoke 124 having a W-shape in plan view. Yoke part 124 a isdisposed at an end surface of permanent magnet 122C in proximity tosecond position detection magnet 15B, and yoke part 124 b is disposed atan end surface of permanent magnet 122D in proximity to second positiondetection magnet 15B.

Yoke parts 123 a and 123 b are used for suppressing intersection of themagnetic flux generated at magnet part 122 and the detection part ofHall device 161, that is, for reducing a leakage flux. With yoke parts123 a and 123 b disposed in the above-mentioned manner, the detectionsensitivity of Hall device 161 is improved. When yoke parts 123 a and123 b are disposed, an attraction force is generated between firstposition detection magnet 15A and yoke parts 123 a and 123 b. Yoke parts124 a and 124 b are disposed for balancing the magnetic force which actson AF movable part 11, and for stabilizing the orientation of AF movablepart 11.

While coupling yokes 123 and 124 are employed in the present embodiment,yoke parts 123 a, 123 b, 124 a, and 124 b may be independent members.

It should be noted that, preferably, yoke parts 123 a and 123 b arecoupled with each other as described in the present embodiment. Withsuch a configuration, the ease of attaching operation is remarkablyreduced in comparison with the case where the yoke part is attached toeach of permanent magnets 122A and 122B. In addition, an attractionforce is generated also between first position detection magnet 15A andthe coupling part that couples yoke part 123 a and yoke part 123 b, andtherefore, by designing coupling yoke 123 such that an attraction forcehaving a desired value is obtained, the thickness of yoke parts 123 aand 123 b can be reduced. Accordingly, the length of permanent magnets122A and 122B can be increased, and therefore the driving performance ofthe AF driving part is improved. Furthermore, the above-mentionedconfiguration is useful for reinforcing the strength of AF fixing part12.

Position detection part 16 is disposed at upper spring fixing part 121 dlocated at the second diagonal part of four upper spring fixing parts121 d of magnet holder 121. Position detection part 16 includes Halldevice 161 that detects variation of the magnetic field by utilizing theHall effect, and position detection substrate 162 for power feeding toHall device 161 and extraction of the detection signal. Hall device 161includes detection part 161 a composed of a semiconductor device (seeFIG. 12), and is disposed such that the detection direction of detectionpart 161 a coincides with the light axis direction. Position detectionpart 16 mainly detects the variation of the magnetic field of firstposition detection magnet 15A. With this configuration, the position ofAF movable part 11 in the light axis direction is detected.

Upper elastic supporting part 13 is a leaf spring formed of berylliumcopper, nickel copper, stainless-steel or the like, for example, and hasa square shape as a whole in plan view. Upper elastic supporting part 13includes upper leaf springs 131 and 132 that elastically support AFmovable part 11 with respect to AF fixing part 12, power-source lineparts 133 and 134 that feed power to Hall device 161, and signal lineparts 135 and 136 that extract a detection signal from Hall device 161.Upper leaf springs 131 and 132, power-source line parts 133 and 134 andsignal line parts 135 and 136 are shaped by punching and cutting a sheetmetal.

Upper leaf spring 131 includes two spring parts 131A and 131B. Springpart 131A includes lens holder fixing part 131 a that is fixed to lensholder 111, magnet holder fixing part 131 b that is disposed at aposition on the radially outside of lens holder fixing part 131 a and isfixed to magnet holder 121, and arm part 131 c that couples lens holderfixing part 131 a and magnet holder fixing part 131 b. Likewise, springpart 131B includes lens holder fixing part 131 d, magnet holder fixingpart 131 e, and arm part 131 f. Lens holder fixing parts 131 a and 131 dare coupled at a position on the inside of arm part 131 c, and magnetholder fixing parts 131 b and 131 e are coupled at a position on theoutside of arm part 131 c.

Lens holder fixing parts 131 a and 131 d include fixation holes 131 gand 131 h corresponding to upper bosses 111 e of lens holder 111. Magnetholder fixing parts 131 b and 131 e include fixation holes 131 i and 131j corresponding to upper bosses 121 e of magnet holder 121. Arm parts131 c and 131 f include folded parts 131 k and 131 m, and extend in awave shape in the XY plane. With such a shape, a twisting moment whichacts on arm parts 131 c and 131 f can be reduced.

Upper leaf spring 131 includes wire connecting part 131 n extending in acurved shape from magnet holder fixing part 131 b. To wire connectingpart 131 n, suspension wire 33B for power feeding to AF coil part 112(see FIG. 4) is connected. Upper leaf spring 131 includes tyingconnection part 131 p extending from lens holder fixing part 131 d.Tying connection part 131 p is connected to one end of AF coil part 112tied to one tying part 111 h of lens holder 111.

Although the shape of upper leaf spring 132 is not completely identicalto that of upper leaf spring 131, their basic structures are similar toeach other, and therefore, the description thereof is omitted. To wireconnecting part 132 n of upper leaf spring 132, suspension wire 33A forpower feeding to AF coil part 112 (see FIG. 4) is connected. Inaddition, tying connection part 132 p is connected to the other end ofAF coil part 112 tied to the other tying part 111 h of lens holder 111.

Power-source line part 133 includes, at both end portions, fixationholes 133 a and 133 b corresponding to upper bosses 121 e of magnetholder 121. Power-source line part 133 includes, at one end portion,wire connecting part 133 c extending in a curved shape. To wireconnecting part 133 c, suspension wire 32A for power feeding to Halldevice 161 (see FIG. 4) is connected. The other end of power-source linepart 133 is connected to power source terminal 162 a of positiondetection substrate 162.

The shape of power-source line part 134 is symmetrical with power-sourceline part 133. To wire connecting part 134 c of power-source line part134, suspension wire 32B for power feeding to Hall device 161 isconnected. In addition, the other end of power-source line part 134 isconnected to power source terminal 162 d of position detection substrate162.

Signal line part 135 includes fixation hole 135 a corresponding to upperboss 121 e of magnet holder 121. Signal line part 135 includes, at oneend portion, wire connecting part 135 b extending in a curved shape. Towire connecting part 135 b, suspension wire 31A for extraction of adetection signal from Hall device 161 (see FIG. 4) is connected. Theother end of signal line part 135 is connected to signal terminal 162 bof position detection substrate 162.

The shape of signal line part 136 is symmetrical with signal line part135. To wire connecting part 136 b of signal line part 136, suspensionwire 31B for extraction of a signal from Hall device 161 is connected.In addition, the other end of signal line part 136 is connected tosignal terminal 162 c of position detection substrate 162.

As with upper elastic supporting part 13, lower elastic supporting part14 is a leaf spring made of beryllium copper, nickel copper,stainless-steel or the like (hereinafter referred to as “lower leafspring 14”), and has a square shape as a whole in plan view. Lower leafspring 14 elastically supports AF movable part 11 with respect to AFfixing part 12. Lower leaf spring 14 is shaped by punching and cutting asheet metal.

Lower leaf spring 14 includes four spring parts 14A to 14D. Each ofspring parts 14A to 14D includes lens holder fixing part 14 a fixed tolens holder 111, magnet holder fixing part 14 b disposed at a positionradially outside of lens holder fixing part 14 a and fixed to magnetholder 121, and arm part 14 c that couples lens holder fixing part 14 aand magnet holder fixing part 14 b. Arm part 14 c has a zigzag shape.

Lens holder fixing parts 14 a adjacent to each other are coupled byinner ring part 14 d. Magnet holder fixing parts 14 b adjacent to eachother are coupled by outer ring part 14 e. Lens holder fixing part 14 aincludes fixation hole 14 f corresponding to lower boss 111 g of lensholder 111. Magnet holder fixing part 14 b includes fixation hole 14 gcorresponding to lower boss 121 i of magnet holder 121.

At the time of assembling OIS movable part 10, first, position detectionpart 16 (Hall device 161 and position detection substrate 162) isattached to magnet holder 121, and coupling yokes 123 and 124 areattached to the yoke housing part (not illustrated) of magnet holder121. Then, upper elastic supporting part 13 is attached to upper springfixing part 121 d.

At this time, one ends of power-source line parts 133 and 134 aresoldered and electrically connected to power source terminals 162 a and162 d of position detection substrate 162. In addition, one ends ofsignal line parts 135 and 136 are soldered and electrically connected tosignal terminals 162 b and 162 c of position detection substrate 162.

Further, a damper (not illustrated) is disposed between folded parts 131m and 131 k of upper leaf spring 131 and magnet holder 121, and betweenfolded parts 132 m and 132 k of upper leaf spring 132 and magnet holder121. With this configuration, generation of unnecessary resonance(high-order resonance mode) is suppressed, and operation stability canbe ensured. The damper can be readily applied by use of a dispenser. Forexample, ultraviolet curing silicone gel can be adopted as the damper.

Next, lower leaf spring 14 is attached to lower spring fixing part 111 fof lens holder 111, and in this state, lens holder 111 is fitted intomagnet holder 121 from the imaging side in the light axis direction. Atthis time, upper spring fixing part 111 d of lens holder 111 is fittedto cutout part 121 c of magnet holder 121. Then, upper leaf springs 131and 132 are attached to upper spring fixing part 111 d of lens holder111. In addition, lower leaf spring 14 is attached to a lower springfixing part (not illustrated) of magnet holder 121.

At this time, tying connection part 131 p of upper leaf spring 131 issoldered and electrically connected to one end of AF coil part 112 tiedto one tying part 111 h of lens holder 111. Likewise, tying connectionpart 132 p of upper leaf spring 132 is soldered and electricallyconnected to the other end of AF coil part 112 tied to the other tyingpart 111 h of lens holder 111.

Next, permanent magnets 122A to 122D are inserted from a regionsurrounded by outer ring part 14 e and arm part 14 c of lower leafspring 14, and bonded to magnet holder 121. At the same time, yoke part123 a of coupling yoke 123 is bonded to an end surface of permanentmagnet 122A in the longitudinal direction, and yoke part 123 b ofcoupling yoke 123 is bonded to an end surface of permanent magnet 122Bin the longitudinal direction. In addition, yoke part 124 a of couplingyoke 124 is bonded to an end surface of permanent magnet 122C in thelongitudinal direction, and yoke part 124 b of coupling yoke 124 isbonded to an end surface of permanent magnet 122D in the longitudinaldirection. In this manner, OIS movable part 10 (AF driving part) isassembled.

As described, lens driving device 1 includes: AF coil part (112)disposed at a periphery of a lens part; AF magnet part (122) having ayoke part (123 a, 123 b, 124 a, 124 b) and disposed separately from AFcoil part (112) in a radial direction; an elastic supporting part (upperleaf springs 131 and 132, lower leaf spring 14) configured toelastically support AF movable part (11) including AF coil part (112)with respect to AF fixing part (12) including AF magnet part (122); andAF driving part (OIS movable part 10) configured to perform automaticfocusing by moving AF movable part (11) in the light axis direction withrespect to AF fixing part (12) by utilizing a driving force of a voicecoil motor composed of AF coil part (112) and AF magnet part (122). Tobe more specific, AF magnet part (122) is composed of four permanentmagnets (122A to 122D) that include yoke part (123 a, 123 b, 124 a, 124b) at an end surface in the longitudinal direction. Four permanentmagnets (122A to 122D) are magnetized in the short direction, anddisposed in a square frame shape.

FIG. 10 is an exploded perspective view of OIS fixing part 20. Asillustrated in FIG. 10, OIS fixing part 20 includes coil substrate 21,sensor substrate 22, base member 23 and the like.

In plan view, coil substrate 21 has a square shape, and has circularopening 21 a at a center portion. Coil substrate 21 includes, at thefour corners, wire fixation holes 21 b through which the other end(lower end) of suspension wire 30 is inserted. In addition, coilsubstrate 21 includes, at positions which intersect the diagonaldirection of peripheral portions of opening 21 a, positioning holes 21c.

Coil substrate 21 includes OIS coil part 211 at a position opposite tomagnet part 122 in the light axis direction. OIS coil part 211 includesfour OIS coils 211A to 211D corresponding to permanent magnets 122A to122D. The sizes and positions of OIS coils 211A to 211D and permanentmagnets 122A to 122D are set such that the magnetic field radiated fromthe bottom surfaces of permanent magnets 122A to 122D traverses the longside portions of OIS coils 211A to 211D in the Z direction. The OISvoice coil motor is composed of magnet part 122 and OIS coil part 211.

As with coil substrate 21, sensor substrate 22 has a square shape inplan view, and has circular opening 22 a at a center portion. Sensorsubstrate 22 includes, at peripheral portions of opening 22 a,positioning holes 22 b at positions corresponding to positioning holes21 c of coil substrate 21. Sensor substrate 22 includes, at the twosides along the X direction, first lock pieces 22 c that are bentdownward. In addition, sensor substrate 22 includes, at the two sidesalong the Y direction, second lock pieces 22 d that are bent downward.The power source terminal and the signal terminal are disposed at secondlock piece 22 d.

Sensor substrate 22 includes power source terminal 22 e for powerfeeding to OIS coil part 211 at four portions of the inner peripheraledge of opening 22 a which intersect the diagonal direction. Inaddition, sensor substrate 22 includes a power-source line (notillustrated) for power feeding to AF coil part 112 and OIS coil part211, and a signal line (not illustrated) for a detection signal outputfrom Hall devices 24A and 24B.

As with coil substrate 21, base member 23 has a square shape in planview, and has circular opening 23 a at a center portion. Base member 23includes, at peripheral portions of opening 23 a, positioning bosses 23b at positions corresponding to positioning holes 21 c of coil substrate21 and positioning holes 22 b of sensor substrate 22. In addition, basemember 23 includes, at the side walls, small recesses 23 c at positionscorresponding to first lock pieces 22 c of sensor substrate 22, andlarge recesses 23 d at positions corresponding to second lock pieces 22d of sensor substrate 22.

In addition, base member 23 includes, at peripheral portions of opening23 a, Hall device housing part 23 f configured to house Hall devices 24Aand 24B, terminal housing part 23 e configured to house power sourceterminal 22 e of sensor substrate 22, and recess 23 g configured toprevent the weld line from overlapping terminal housing part 23 e havinga small thickness.

Hall devices 24A and 24B are disposed on the rear surface side of sensorsubstrate 22, and are housed in Hall device housing part 23 f of basemember 23. By detecting the magnetic field formed by magnet part 122with Hall devices 24A and 24B, the position of OIS movable part 10 inthe XY plane can be specified. It is to be noted that an XY-positiondetection magnet may be disposed at OIS movable part 10 in addition tomagnet part 122.

At the time of assembling OIS fixing part 20, first, coil substrate 21and sensor substrate 22 are bonded by soldering. In this manner, thepower-source line (not illustrated) of sensor substrate 22 and OIS coilpart 211 are electrically connected to each other.

Next, positioning holes 21 c of coil substrate 21 and positioning holes22 b of sensor substrate 22 are fitted to positioning bosses 23 b ofbase member 23 to dispose coil substrate 21 and sensor substrate 22 onbase member 23. First lock pieces 22 c of sensor substrate 22 areengaged with small recesses 23 c of base member 23, and second lockpieces 22 d of sensor substrate 22 are engaged with large recesses 23 d,and thus, coil substrate 21 and sensor substrate 22 are fixed to basemember 23. In this manner, OIS fixing part 20 are assembled.

As described, lens driving device 1 includes: OIS magnet part (magnetpart 122) disposed at an AF unit including AF movable part (11) and AFfixing part (12); OIS coil part (211) disposed separately from OISmagnet part (122) in a light axis direction; and an OIS driving partconfigured to perform shake correction by swinging OIS movable part (10)including OIS magnet part (122) in a plane orthogonal to the light axisdirection with respect to OIS fixing part (20) including OIS coil part(211) by utilizing a driving force of a voice coil motor composed of OIScoil part (211) and OIS magnet part (122).

At the time of assembling lens driving device 1, one ends of suspensionwires 33A and 33B are respectively inserted to wire connecting part 132n of upper leaf spring 132 and wire connecting part 131 n of upper leafspring 131, and fixed thereto by soldering. One ends of suspension wires32A and 32B are respectively inserted to wire connecting part 133 c ofpower-source line part 133 and wire connecting part 134 c ofpower-source line part 134 and fixed thereto by soldering. One ends ofsuspension wires 31A and 31B are respectively inserted to wireconnecting part 135 b of signal line part 135 and wire connecting part136 b of signal line part 136, and fixed thereto by soldering. With thisconfiguration, suspension wire 30, and upper leaf springs 131 and 132,power-source line parts 133 and 134, and signal line parts 135 and 136are electrically connected together.

Next, the other end (lower end) of suspension wire 30 is inserted towire fixation hole 21 b of coil substrate 21, and is fixed by soldering.In this manner, the power-source line and the signal line of sensorsubstrate 22 and suspension wire 30 are electrically connected to eachother. That is, it is possible to perform power feeding to AF coil part112 and Hall device 161 and operation control of Hall device 161 throughsuspension wire 30 and upper elastic supporting part 13.

Here, a damper (not illustrated) is disposed at wire insertion part 121g of magnet holder 121 so as to surround suspension wire 30. Thus thedamper is interposed between magnet holder 121 and upper elasticsupporting part 13. By interposing the damper (not illustrated) betweenmagnet holder 121 and upper elastic supporting part 13, generation ofunnecessary resonance (high-order resonance mode) can be reduced, andconsequently, the stability of the operation can be ensured. The dampercan be readily applied to wire insertion part 121 g with use of adispenser. For example, ultraviolet curing silicone gel can be adoptedas the damper.

In addition, wire connecting parts 131 n and 132 n of upper leaf springs131 and 132, wire connecting parts 133 c and 134 c of power-source lineparts 133 and 134, and wire connecting parts 135 b and 136 b of signalline parts 135 and 136 are formed in a curved shape so as to be easilyelastically deformed. The drop impact is absorbed by deflection of theabove-mentioned parts and suspension wire 30, and therefore plasticdeformation or rupture of suspension wire 30 does not occur.

Shield cover 2 is attached to lens driving device 1 in such a mannerthat engagement piece 2 b of shield cover 2 makes contact with firstlock piece 22 c of sensor substrate 22. Since small recess 23 c of basemember 23 has a tapered shape, a biasing force acts between first lockpiece 22 c of sensor substrate 22 and engagement piece 2 b of shieldcover 2. Accordingly, shield cover 2 and sensor substrate 22 areelectrically connected to each other without soldering. In this manner,shield cover 2 can be readily grounded, and EMC noise can be blocked.

At the time of shake correction in lens driving device 1, OIS coil part211 is energized. When OIS coil part 211 is energized, a Lorentz forceis generated at OIS coil part 211 by interaction between the magneticfield of magnet part 122 and the current flowing through OIS coil part211 (Fleming's left hand rule). The direction of the Lorentz force isthe direction (the Y direction or the X direction) orthogonal to thedirection of the magnetic field (the Z direction) and to the directionof the current flowing through the long side portion of OIS coil part211 (the X direction or the Y direction). Since OIS coil part 211 isfixed, a reactive force acts on magnet part 122. With this reactiveforce serving as the driving force of the OIS voice coil motor, OISmovable part 10 including magnet part 122 sways in the XY plane, andthus shake correction is performed.

At the time of automatic focusing in lens driving device 1, AF coil part112 is energized. When AF coil part 112 is energized, a Lorentz force isgenerated at AF coil part 112 by interaction between the magnetic fieldof magnet part 122 and the current flowing through AF coil part 112. Thedirection of the Lorentz force is a direction (the Z direction)orthogonal to the direction of the magnetic field (X direction or Ydirection) and to the direction of the current flowing through the AFcoil part 112 (the Y direction or the X direction). Since magnet part122 is fixed, a reactive force acts on AF coil part 112. With thisreactive force serving as the driving force of the AF voice coil motor,AF movable part 11 including AF coil part 112 moves in the light axisdirection, and thus focusing is performed.

Here, in an non-energization state where focusing is not performed, AFmovable part 11 is suspended between the infinity position and the macroposition with upper leaf springs 131 and 132 and lower leaf spring 14(hereinafter referred to as “reference state”). That is, in OIS movablepart 10, AF movable part 11 (lens holder 111) is elastically supportedsuch that AF movable part 11 is displaceable in the Z direction in thestate where the position of AF movable part 11 with respect to AF fixingpart 12 (magnet holder 121) is set by upper leaf springs 131 and 132,and lower leaf spring 14.

At the time of focusing, the direction of the current is controlledbased on whether AF movable part 11 is moved from the reference statetoward the macro position side or toward the infinity position side. Inaddition, the value of the current is controlled based on the movementlength of AF movable part 11.

When AF movable part 11 moves to the infinity position side at the timeof focusing, the bottom surface of protruding part 111 b of lens 111holder approaches the top surface of magnet part 122, and finally makescontact with the top surface of magnet part 122. That is, the movementto the infinity position side is restricted by the bottom surface ofprotruding part 111 b of lens holder 111 and the top surface of magnetpart 122. When AF movable part 11 moves to the macro position side atthe time of focusing, the top surface of protruding part 111 b of lensholder 111 approaches the bottom surface of stopper part 121 b of magnetholder 121, and finally makes contact with the bottom surface of stopperpart 121 b. That is, the movement to the macro position side isrestricted by the top surface of protruding part 111 b of lens holder111 and the bottom surface of stopper part 121 b of magnet holder 121.

Further, in the AF driving part of lens driving device 1, a closed loopcontrol is performed based on a detection signal of position detectionpart 16. With the closed loop control method, the hysteresischaracteristics of the voice coil motor are not required to beconsidered, and the stability of the position of AF movable part 11 canbe directly detected. Furthermore, automatic focusing of an imagesurface detection method can be adopted. Accordingly, with highresponsiveness, speedup of the automatic focusing operation can beachieved.

FIG. 11 is a plan view illustrating the positions of Hall device 161 andposition detection magnet 15. FIG. 12 is a side view illustrating thepositions of Hall device 161 and first position detection magnet 15A.FIG. 13 is a perspective view illustrating the positions of Hall device161 and position detection magnet 15. In FIGS. 11 to 13, only AF coilpart 112 is illustrated in AF movable part 11, and only magnet part 122and coupling yokes 123 and 124 are illustrated in AF fixing part 12 forthe purpose of clearly showing the positions of Hall device 161 andposition detection magnet 15.

In the case where Hall device 161 is disposed at AF fixing part 12 andfirst position detection magnet 15A is disposed at AF movable part 11,it is desirable that the detection part of Hall device 161 intersectonly the magnetic flux of first position detection magnet 15A. However,in the case where magnet part 122 is composed of four permanent magnets122A to 122D and permanent magnets 122A to 122D are disposed in a squareframe shape as in the present embodiment, the region for installing Halldevice 161 is significantly limited, and therefore the influence of theleakage flux of magnet part 122 cannot be completely eliminated. Thatis, the detection part of Hall device 161 intersects the leakage flux ofmagnet part 122 to a certain degree. Consequently, the influence of theleakage flux of magnet part 122 results in an output voltage offset, andthe dynamic range of the detection sensitivity is significantly reduced.

In the present embodiment, Hall device 161 is disposed at a positionwhere the influence of the leakage flux of magnet part 122 is minimized.Specifically, since the influence of the leakage flux of magnet part 122is minimized at the diagonal parts located at the four vertexes of thequadrangle, Hall device 161 is disposed at one of the second diagonalparts. In addition, Hall device 161 is disposed such that the detectiondirection of detection part 161 a coincides with the light axisdirection. In this case, the detection direction of Hall device 161 issubstantially perpendicular to the leakage flux of magnet part 122. Itis preferable to set the distance between Hall device 161 and magnetpart 122 to a large value as much as possible as long as lens drivingdevice 1 is not upsized. By disposing Hall device 161 in theabove-mentioned manner, the influence of the leakage flux of magnet part122 can be minimized.

On the other hand, first position detection magnet 15A disposed at AFmovable part 11 is disposed at a position close to Hall device 161 asmuch as possible. In addition, first position detection magnet 15A isdisposed such that the magnetization direction coincides with the lightaxis direction. With this configuration, the effective magnetic fluxwhich intersects the detection part of Hall device 161 increases, andconsequently the detection sensitivity of Hall device 161 is improved.It is to be noted that second position detection magnet 15B is disposedat a position point symmetrical with first position detection magnet 15Aabout the optical axis.

As described, lens driving device 1 includes: Hall device (161) disposedseparately from AF magnet part (magnet part 122) in the light axisdirection at a position corresponding to one diagonal part (one ofsecond diagonal parts) of AF magnet part (122) such that the detectiondirection coincides with the light axis direction; first positiondetection magnet (15A) disposed at a position near Hall device (161)such that the magnetization direction coincides with the light axisdirection; and second position detection magnet (15B) having aconfiguration similar to that of first position detection magnet (15A)and disposed at a position point symmetrical with first positiondetection magnet (15A) about the light axis direction.

With lens driving device 1, the influence of the leakage flux of magnetpart 122 can be minimized, and the detection sensitivity of Hall device161 is improved, and therefore, the position of AF movable part 11 inthe light axis direction can be accurately detected. Accordingly, lensdriving device 1 can achieve downsizing and power saving, and is usefulfor the case where automatic focusing is performed by a closed loopcontrol method.

Here, the leakage flux of magnet part 122 has an influence not only onthe detection sensitivity of Hall device 161, but also on the magneticforce which acts on first position detection magnet 15A. That is, in thecase where the parts of first position detection magnet 15A and magnetpart 122 close to each other have the same polarity, a repulsive forceis generated therebetween, and in the case where the parts have oppositepolarities, an attraction force is generated therebetween (see FIG. 13).While FIG. 13 illustrates an attraction force generated between firstposition detection magnet 15A and yoke part 123 b and a repulsive forcegenerated between first position detection magnet 15A and permanentmagnet 122B, an attraction force is generated also between firstposition detection magnet 15A and yoke part 123 a, and a repulsive forceis generated also between first position detection magnet 15A andpermanent magnet 122A. The same applies to the magnetic force generatedat second position detection magnet 15B.

Since detection magnet 15B is disposed at the second position which ispoint symmetrical with first position detection magnet 15A about theoptical axis, the translational acting force in the XY plane is offset.Accordingly, it suffices to consider the acting force of AF movable part11 in the movement direction (the Z direction) as the acting force on AFmovable part 11. Since the acting force in the Z direction to AF movablepart 11 interferes with the movement operation of AF movable part 11, itis preferable that the acting force in the Z direction to AF movablepart 11 be small as much as possible.

In the present embodiment, permanent magnet 122A includes yoke part 123a at the end surface in proximity to first position detection magnet15A. In addition, permanent magnet 122B includes yoke part 123 b at theend surface in proximity to first position detection magnet 15A. Withyoke parts 123 a and 123 b thus disposed, the leakage flux of magnetpart 122 is reduced, and the magnetic force (repulsive force orattraction force) between magnet part 122 and first position detectionmagnet 15A is reduced. Accordingly, the acting force in the movementdirection to AF movable part 11 due to the leakage flux of magnet part122 (hereinafter referred to as “acting force in the movement direction”or “acting force in the Z direction”) is reduced.

In addition, when yoke parts 123 a and 123 b are disposed, the parts offirst position detection magnet 15A and magnet part 122 close to eachother preferably have the same polarity. In this case, the parts ofsecond position detection magnet 15B and magnet part 122 close to eachother also have the same polarity. A part or all of an attraction forcegenerated between first position detection magnet 15A and yoke parts 123a and 123 b is offset by a repulsive force generated between magnet part122 and first position detection magnet 15A, and the acting force in theZ direction to AF movable part 11 is further reduced.

As described above, while the acting force in the Z direction to AFmovable part 11 can be reduced, the acting force in the Z directionvaries along with the movement operation of AF movable part 11. In viewof this, as illustrated in FIG. 14, it is preferable to select thepositions and the types of first position detection magnet 15A andsecond position detection magnet 15B such that the acting force in the Zdirection to AF movable part 11 is 0 at the reference position, and thatthe repulsive force is predominant and the acting force in the Zdirection of +direction is generated when AF movable part 11 is moved tothe light reception side in the light axis direction whereas theattraction force is predominant and the acting force in the Z directionof −direction is generated when AF movable part 11 is moved to the imagepickup side in the light axis direction.

In this case, first position detection magnet 15A, second positiondetection magnet 15B, and magnet part 122 can be regarded as springsopposite to upper leaf springs 131 and 132, and lower leaf spring 14.That is, when AF movable part 11 is moved, the acting force in the Zdirection is generated in the direction opposite to the biasing force(restoration force) generated at upper leaf springs 131 and 132 andlower leaf spring 14.

As described, lens driving device 1 includes an auxiliary magnet(position detection magnet 15) in which the acting force in the Zdirection to AF movable part (11) is 0 at the reference position of AFmovable part (11), and the acting force in the Z direction is generatedin the direction opposite to the restoration force of the elasticsupporting part when AF movable part (11) is moved. To be more specific,auxiliary magnet (15) includes a first auxiliary magnet (first positiondetection magnet 15A) disposed separately from AF magnet part (magnetpart 122) in the light axis direction and disposed at a positioncorresponding to one diagonal part of AF magnet part (122), and a secondauxiliary magnet having a configuration similar to that of firstauxiliary magnet (15A) and disposed at a position point symmetrical withfirst auxiliary magnet (15A) about the light axis direction.

With this configuration, even when the rigidity of upper leaf springs131 and 132 and lower leaf spring 14 is increased, a desired springconstant as a whole can be achieved. By increasing the rigidity of upperleaf springs 131 and 132 and lower leaf spring 14, the frequency of theunnecessary resonance is increased, and the servo stability is improved,and therefore, the degree of freedom of the servo design is increased.In addition, the OIS tilt characteristics can be improved.

While the invention made by the present inventor has been specificallydescribed based on the preferred embodiments, it is not intended tolimit the present invention to the above-mentioned preferred embodimentsbut the present invention may be further modified within the scope andspirit of the invention defined by the appended claims.

While lens driving device 1 has an AF function and an OIS function inthe embodiment, the present invention may also be applied to a lensdriving device having only an AF function, for example. In addition,while yoke parts 123 a, 123 b, 124 a, and 124 b are disposed atrespective end surfaces of permanent magnets 122A to 122D in thelongitudinal direction, yoke parts 123 a, 123 b, 124 a, and 124 b may beomitted.

While a smartphone is described in the embodiment as an example of thecamera-equipped mobile terminal, the present invention is alsoapplicable to camera-equipped mobile phones, note-type personalcomputers, tablet terminals, mobile game machines, webcameras,in-vehicle cameras and the like.

The embodiment disclosed herein is merely an exemplification and shouldnot be considered as limitative. The scope of the present invention isspecified by the following claims, not by the above-mentioneddescription. It should be understood that various modifications,combinations, sub-combinations and alterations may occur depending ondesign requirements and other factors in so far as they are within thescope of the appended claims or the equivalents thereof. Althoughembodiments of the present invention has been described and illustratedin detail, it is clearly understood that the same is by way ofillustrated and example only and is not to be taken by way oflimitation, the scope of the present invention being interpreted byterms of the appended claims.

This application is entitled to and claims the benefit of JapanesePatent Application No. 2014-143591 dated Jul. 11, 2014, the disclosureof which including the specification, drawings and abstract isincorporated herein by reference in its entirety.

REFERENCE SIGNS LIST

-   1 Lens driving device-   2 Shield cover-   10 OIS movable part (AF driving part)-   11 AF movable part-   111 Lens holder-   112 AF coil part-   12 AF fixing part-   121 Magnet holder-   122 Magnet part (AF magnet part, OIS magnet part)-   122A to 122D Permanent magnet-   13 Upper elastic supporting part-   131, 132 Upper leaf spring-   133, 134 Power-source line part-   135, 136 Signal line part-   14 Lower elastic supporting part, lower leaf spring-   15 Position detection magnet-   15A First position detection magnet (first auxiliary magnet)-   15B Second position detection magnet (second auxiliary magnet)-   16 Position detection part-   161 Hall device-   162 Position detection substrate-   20 OIS fixing part-   21 Coil substrate-   211 OIS coil part-   211A to 211D OIS coil-   22 Sensor substrate-   23 Base member-   30 Supporting member-   31A, 31B Signal suspension wire-   32A, 32B Hall device feeding suspension wire-   33A, 33B Coil feeding suspension wire-   M Smartphone-   A Camera module

The invention claimed is:
 1. A lens driving device comprising: anauto-focusing driving part, and an auxiliary magnet, the auto-focusingdriving part including: an auto-focusing coil part disposed at aperiphery of a lens part; an auto-focusing magnet part having a yokepart and disposed separately from the auto-focusing coil part in aradial direction; and an elastic supporting part configured toelastically support an auto focus movable part including theauto-focusing coil part with respect to an auto focus fixing partincluding the auto-focusing magnet part; the auto-focusing driving partbeing configured to perform automatic focusing by moving the auto focusmovable part in a light axis direction with respect to the auto focusfixing part by utilizing a driving force of a voice coil motor composedof the auto-focusing coil part and the auto-focusing magnet part; theauxiliary magnet being configured to have no acting force in a movementdirection with respect to the auto focus movable part at a referenceposition of the auto focus movable part, and being configured togenerate an acting force in a movement direction in a direction oppositeto a direction of a restoration force of the elastic supporting partwhen the auto focus movable part is moved, wherein the auto-focusingmagnet part is composed of four permanent magnets which are disposed ina square frame shape, each of the permanent magnets including the yokepart at an end surface in a longitudinal direction and being configuredto be magnetized in a short direction; and the auxiliary magnetincludes: a first auxiliary magnet disposed separately from theauto-focusing magnet part in the light axis direction at a positioncorresponding to one diagonal part of the auto-focusing magnet part; anda second auxiliary magnet having a configuration similar to that of thefirst auxiliary magnet and disposed at a position symmetrical with aposition of the first auxiliary magnet about the light axis direction.2. The lens driving device according to claim 1, wherein the yoke partsadjacent to each other are coupled with each other.
 3. The lens drivingdevice according to claim 1, wherein the auto focus movable partincludes a lens holder, the lens holder includes: a coil winding partfor disposing the auto-focusing coil part; a tying part for tying bothends of the auto-focusing coil part; and wherein the tying part isformed to protrude outward in a radial direction and has a tapered shapewhose diameter is reduced toward an inner side in the radial direction.4. The lens driving device according to claim 1 further comprising ashake-correcting driving part, the shake-correcting driving partincluding: a shake-correcting magnet part disposed at an auto focus unitincluding the auto focus movable part and the auto focus fixing part;and a shake-correcting coil part disposed separately from theshake-correcting magnet part in the light axis direction; theshake-correcting driving part being configured to perform shakecorrection by swinging a shake-correcting movable part including theshake-correcting magnet part in a plane orthogonal to the light axisdirection with respect to a shake-correcting fixing part including theshake-correcting coil part by utilizing a driving force of a voice coilmotor composed of the shake-correcting coil part and theshake-correcting magnet part.
 5. The lens driving device according toclaim 4, wherein the auto-focusing magnet part serves also as theshake-correcting magnet.
 6. A camera module comprising: the lens drivingdevice according to claim 1; a lens part mounted to the auto focusmovable part; and an image capturing part configured to capture asubject image imaged by the lens part.
 7. A camera-equipped mobileterminal comprising the camera module according to claim 6.